Use vcpkg to set up pkgconf and hwloc in Windows CI

[HadrienG2]

It's a bit of a mess, but it can be made to work. See https://numerical-rust-cpu-d1379d.pages.math.cnrs.fr/setup/windows.html#pkgconf-hwloc-and-hdf5 for reference, removing hdf5.

[HadrienG2]

This is also a pretty credible path to finally resolving #21.